The woman also told police that her husband forced her into sex trafficking over the past two years.
She also told authorities the body of her "baby" - 6-year-old Alyssa - could be found in the Centreville garage at 7201 Russell Ave.
We found IL court records showing Quate was arrested on a warrant in July of 2000 and found guilty on two felony charges of burglary.
Quate's wife said her husband killed the 6-year-old girl, the youngest of their children, "during a physical altercation", according to the Associated Press.
Now authorities in St. Clair County are trying to determine whether a 7-year-old child whose body was found decomposed inside a garage Tuesday was the victim of a homicide or natural death.
Las Vegas police Lt. Raymond Spencer told the St. Louis-Dispatch that the woman who tipped police to the decomposing remains went to police to report that not only was her husband forcing her into prostitution but abusing two of the children in their home, who were kept in strict isolation.
According to CBS affiliate KMOV, the unidentified woman said that she moved with her husband, 34-year-old Jason Quate, and their two teenage daughters from IL to Las Vegas about two years ago. Officers in Nevada are working with the Metro East authorities who are investigating the child's death, she said. Quate has not been charged in his daughter's death.
Quate told the St. Louis newspaper that the girl choked when he spanked her, unaware she still had Salisbury steak in her mouth.
Detectives authored a search warrant for the Las Vegas address, and in the early morning hours of June 6, LVMPD SWAT officers assisted with the service of that search warrant.
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He also addressed a statement he made to the Las Vegas TV station on Wednesday - that his wife had told him in 2013 that she had found a family to adopt their daughter.
He repeatedly referred to the event as "the terrible".
Las Vegas police said the tip about the child's body stemmed from an unrelated investigation there.
The remains were discovered in Centreville, a suburb a few miles southeast of St. Louis in Illinois' St. Clair County.
Neighbors of the small, frame home with boarded-up windows told the Belleville News-Democrat the house has been vacant for more than two years. Their two teenage daughters are now in protective custody.
Las Vegas police said they received one call in February 2017 to check the welfare of occupants at the Quates' address.
Spencer said officers were told the woman's remaining children, who are in their early teens, were never allowed outside, even to attend school.